2.3 ASIC, FPGA, and DDR rail power design through PMBus power supplies- Part 3: PMBus in Manufacturing

Hi. This is ASIC, FPGA, and DDR rail power design for PMBus power supplies, and here we're going to talk about how we can implement PMBus in manufacturing, and what are some of the common PMBus usage examples. So how can we implement PMBus in manufacturing? Well, the good news is the TI Fusion GUI Digital Power Designer also has a manufacturing tool.
So first we use the Fusion Configuration Tool to select the settings for the rails of the voltage regulators on the board. Once we have selected the settings, we export the settings to a file, and then we load this configuration file into the manufacturing GUI. The PMBus programmer script is very easy. It's a device neutral way to specify the programming steps required to write and verify the values in the IC NVM, non-volatile memory.
Equipment vendors only need to do programming algorithm development one time to cover all TPS devices that will use this format. The script flow goes like this-- first you verify the correct part present via the device called PMBus command read, then you write the configuration to the volatile memory via PMBus, then you execute PMBus store all command to save this configuration from the volatile memory to the non-volatile memory.
Then you reset the power to the device, and finally you read back the configuration via PMBus to confirm the values are correct. This takes into account device time and requirements, and the text file in offered in a comma separated value CSV format. And here's an example below. On the left you will see all the write commands that you use to write the commands and their values into the IC.
In this case the IC we use is our dual-buck controller, also configurable as a dual phase controller, TPS 40422. So first you read the value of the device to make sure you're writing into the correct device, and then you start writing the commands. First you write whatever information you want to save into the user scratch pad.
It could be project name, project revision, project phase, et cetera. Then you write the manufacturer 21 command in this case to enable the analog to digital converter of that buck controller to measure, to monitor output voltage, current, and temperature, and you also program the dead time between channel one and channel two DA drivers.
Then you write the on off configuration mode. In this case we have selected always converting. In other words, when the power supply is present to the IC, the IC can start converting. Then we write the I out, called gain value, to calibrate out any gain errors from the output current monitoring that is offered by the IC. Finally, you store this configuration to the data flash by executing the store user all command.
Then you reset the power to the device, and you read back the values that you wrote it, such as a user scratch pad, manufacturer 21 for the ADC and the channel one, and channel two dead time, the on off configuration value, as well as the I out cal gain correction value. Finally, after you verify that the values are correct, you end the script, and the manufacturing script is ready for use.
A lot of customers have JTAG ports, and we have gotten questions about using the JTAG port to program through PMBus Our sequencers offer that capability, but our TPS 54k buck converters and TPS 40k controllers do not offer that capability yet. In the meantime, you can use a JTAG to PMBus adaptor.
Basically, this adapter accepts a JTAG interface communication in, and has load devices, like CPUs, toggle the clock and data lines on RPM bus devices to emulate [INAUDIBLE] communication as described in a JTAG script. Keep in mind, though, that our voltage regulator devices at this time support, by default, SMBus PMBus communication.
So, what are some of the PMBus usage examples? First, you can obviously use PMBus to configure your power supply in the lab. This offers fast and easy evaluation, and you don't have to use any external components to program the power supplies, or the current limit settings, the under voltage lookout settings, the soft starter switching frequency settings. All that is done through PMBus.
You can also use PMBus in the factory. You customize your board and the power system on your board during manufacturing, using the manufacturing automated test equipment that you see here. You can also use PMBus in a system, and develop a real time dashboard to monitor, optimize, and manage faults. This is done by some of our customers, and they use PMBus for remote monitoring of their systems out in the field.
TI offers PMBus DC to DC conversion end to end. Here you see a 48 to point of load PMBus system. It is comprised of a 48 volt hot-swap controller with PMBus to monitor end report, the input voltage and input current, a 48 volt isolated PWM controller in a Fullbridge configuration-- it used to be 3138-- and 12 volt input PMBus point of load controllers, in this case the TPS40422 with an external TI power block.
For more resources, please visit these links below. Tune in for the next segment that talks about what PMBus telemetry does, and what types of PMBus power supply ICs TI offers.